In a world increasingly influenced by the existence of networks connecting a widespread array of computing resources, the topics of data security, information protection, and user privacy have never been more important. Personal computers (PCs) typically offer an open architecture as an industry standard which can be used to build a ubiquitous computing platform. Trust in the platform, however, has not commonly been part of such designs. As used herein, the term “platform” can be taken to mean any type of device, including hardware, firmware, software, or any combination of these, whose activity is directed according to a plurality of programmed instructions.
Typically, platforms execute under the control of an Operating System (OS) when applications are to be executed. Operating Systems and pre-Operating System components are complex and require a loading (i.e., “boot”) process to load them into the platform's memory. The platform loads the OS when the platform transitions from a power-off or suspend state to a power-on state, or when a reset signal is applied to the platform's reset line. Herein, the term “platform reset” may be used to refer to any of these conditions. The platform initialization code includes two components: the Platform Initialization Boot Block (PIBB) and the Main Platform Initialization Code (MPIC). After a platform reset occurs, the central processing unit (CPU) begins execution at a well known and defined location within the PIBB. This code is intentionally small, robust, and secure. The PIBB executes code to enable devices on the platform necessary for the Main Platform Initialization Code to execute. The PIBB then passes control of the platform to the Main Platform Initialization Code.
The Main Platform Initialization Code performs necessary functions to complete the initialization of the platform. Such functions may include initializing devices embedded within the platform, and locating and initializing optional plug-in or embedded adapters (having their own device initialization code). After this, the Main Platform Initialization Code locates the OS Loader and executes it. The OS Loader, in turn, loads the OS into memory and begins executing the OS. At this point, the platform is considered in the OS-present state and is fully under control of the loaded OS.
Whenever an untrusted platform loads an OS, violations of security policies can result without ever connecting the platform to a network. Thus, trusted computing is gaining importance in all aspects of computational operations, even when such operations are conducted apart from a network.